Just as she has moved on, I suspect that he wants to move on as well. But, he probably cannot get another mortgage without retiring the first one.
If I were her, I would get together with him, possible with the assistance of her divorce attorney, and just state that her credit post chapter 13 just is not good enough to get refinancing. They both jointly file an amendment to the existing court order and state that the house is to be listed for sale instead. If there is any profit, they split it in whatever manner seems equitable. If the house cannot be sold for the outstanding mortgage balance, then he will seek approval for a short sale. Since they were both in a chapter 13 bankruptcy, I can't say that a short sale will damage either person's credit any more than it has already been damaged. But, with only his name on the mortgage, he is going to be the one who will have to approach the lender about a short sale.
You two negotiate a move out date. You don't like the place anyway. So, you might as well vacate it and get this issue resolved once and for.